Japan Geoscience Union Meeting 2022

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[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS03] Large-scale moisture and organized cloud systems

Wed. May 25, 2022 10:45 AM - 12:15 PM 106 (International Conference Hall, Makuhari Messe)

convener:Satoru Yokoi(Japan Agency for Marine-Earth Science and Technology), convener:Hiroaki Miura(The University of Tokyo), Atsushi Hamada(University of Toyama), convener:Daisuke Takasuka(Japan Agency for Marine-earth Science and Technology), Chairperson:Daisuke Takasuka(Japan Agency for Marine-earth Science and Technology), Atsushi Hamada(University of Toyama)

10:45 AM - 11:00 AM

[AAS03-06] Process-level Assessment of the Iris Effect over Tropical Oceans

Masato Ito1, *Hirohiko Masunaga1 (1.Nagoya University)

Keywords:Cloud-radaition feedback, Tropical convection

The iris hypothesis suggests a cloud feedback mechanism that a reduction in the tropical anvil cloud fraction (CF) in a warmer climate may act to mitigate the warming by enhanced outgoing longwave radiation. Two different physical processes, one involving precipitation efficiency and the other focusing on upper-tropospheric stability, have been argued in the literature to be responsible for the iris effect. In this study, A-Train observations and reanalysis data are analyzed to assess these two processes. Major findings are as follows: (1) the anvil CF changes evidently with upper-tropospheric stability as expected from the stability iris theory, (2) precipitation efficiency is unlikely to have control on the anvil CF but is related to mid- and low-level CFs, and (3) the day and nighttime cloud radiative effects are expected to largely cancel out when integrated over a diurnal cycle, suggesting a neutral cloud feedback.